Rotary piston machine



Oct. 15, 1968 A. w. SPARROW 3,405,693

ROTARY PISTON MACHINE Filed Sept. 1, 1966 6 Sheets-Sheet 1 AZ/W WYCL/Fff SPA/WOW A ttameys Get. 15, 1968 A. w. SPARROW 3,405,693

ROTARY PISTON MACHINE Filed Sept. 1, 1966 6 Sheets-Sheet 2 /5a 28a 29a 5 Inventor AM/V W)6Z/FF SPA/WOW 5m k Mwk Attorneys Oct. 15, 1968 A. w. SPARROW 3,405,693

ROTARY PISTON MACHINE Filed Sept. 1, 1966 1 6 Sheets-Sheet 5 Inventor ALA N W YCL /FF SPARROW A tlomeys 0a. 15 1968 A. w. SPARROW 3,405,693

ROTARY PISTON MACHINE Filed Sept. 1; 1966 s Sheets-Sheet Inventor AZ/l/V WyCZ/F/f SPARROW B Slum A tlorneys Oct. 15, 1968 A. w. SPARROW 3,405,693

ROTARY PISTON MACHINE Filed Sept. 1, 1966 6 Sheets-Sheet 5 lnvenlor ALA/V WYCL/Ff' SPAR/4 0W 52" Q [l lt d tlorneys Oct. 15, 1968 A. w. SPARROW 3,405,593

ROTARY PISTON MACHINE Filed Sept. 1, 1966 6 Sheets-Sheet 6 ventor In ALA/V WYCA/fff SPARROW y QW MM Attorneys United States Patent 3,405,693 ROTARY PISTON MACHINE Alan W. Sparrow, Peterborough, England, assignor to Perkins Engines Limited, London, England Filed Sept. 1, 1966, Ser. No. 576,647 Claims priority, application Great Britain, Sept. 10, 1965, 38,837 65 18 Claims. (Cl. 1238) ABSTRACT OF THE DISCLOSURE A rotary piston machine having a trochoidal cavity housing, a fixed shaft extending through the housing having teeth thereon, a power transmitting member carried on and surrounding the stationary shaft arranged to transmit power into or out of the machine, a piston member rotatably carried on an eccentric portion of the power transmitting member and having internal teeth that mesh with the teeth on the stationary shaft. Various combina tions of multiple piston engines are also disclosed.

This invention relates to rotary piston machines and more particularly to rotary piston internal combustion engines.

In one known rotary piston internal combustion engine such as that disclosed in United States Patent Number 2,998,065, a lobed rotor or rotary piston rotates in a suitably shaped cavity, the rotor and cavity defining chambers whose volumes vary as the rotor rotates. The rotor is mounted on an eccentric carried by a shaft, and gear teeth on the rotor cooperate, either directly or through idler wheels, with a ring of stationary gear teeth suitably positioned on the engine housing. The gearing dictates the manner in which the rotor rotates in the cavity, and the shape of the cavity. For example, if the gear ratio is 3:2 the cavity is double lobed epitrochoidal and the rotor is three-lobed. A disadvantage of this arrangement is that the shaft, which is the output shaft, must pass through the ring of gear teeth and may result in the shaft being of a diameter which may be too small for the loads involved. The gear teeth ring diameters are usually fixed for the engine involved and therefore, cannot be varied.

It is therefore an object of the present invention to provide a rotary piston machine wherein the power transmitting element can be formed of a relatively large diameter to provide a large torque carrying capacity.

It is another object of the invention to provide a rotary piston machine having a stationary, non-rotatable shaft surrounded by a power transmitting member having an eccentric portion carrying the rotary piston, the shaft serving to carry coolant into and out of the machine.

These and other objects and advantages will be readily apparent from the following description and accompanying drawings in which:

FIG. 1 shows a cross-section through a rotary piston machine according to the invention;

FIG. 2 shows in upper and lower halves respectively, the cross-sections on line 22 of FIG. 1;

FIG. 3 shows a cross-section through another rotary piston machine according to the invention;

FIG. 4 shows a cross-section through a further rotary piston machine according to the invention;

FIG. 5 shows a cross-section through a still further rotary piston machine according to the invention; and

FIGS. 6 to 11 show clusters of rotary piston machines as shown in FIGS. 1 to 5.

Briefly, the invention includes a rotary piston machine including a housing having a cavity with a trochoidal periphery, a fixed shaft is carried by the housing and has gear teeth thereon. A power transmitting member is rotatably carried on the shaft and a rotary piston having a plural apex configuration is rotatably carried on an eccentric portion, formed on the power transmitting member. The piston member has internal gear teeth that mesh with the teeth on the shaft.

The power transmitting member carries a flywheel as well as a counter balance portion offsetting the eccentric portion. The fixed shaft serves to carry coolant into and out of the interior of the machine to cool the housing, the shaft, the piston, the bearings, etc. A multiple piston engine can easily be built up using a common fixed shaft and a common power transmittin member having a plurality of eccentric portions therein each carrying a multi-lobed annular piston member.

Referring to FIG. 1, a rotary piston machine, in this case a single rotary piston engine, has a housing 10 made up of a peripheral wall 13, and spaced end walls consisting of a bottom outer end wall 11, a bottom inner end wall 12, a top inner end wall 14 and a top outer end wall 15. A shaft 16 non-rotatably supported in end walls 11 and 15 has journalled on it an eccentric carrying member 17A having an integral eccentric 17. Rotatably supported on the eccentric 17 is a three cornered rotary piston 18, which moves in a two lobed cavity 19 defined by the peripheral wall 13 and the top and bottom chamber end walls 12 and 14 of the housing 10, and which defines with these walls three working chambers 20 of variable volume.

The shaft 16 carries a set of spur gear teeth 21 and the eccentric carrying member 17A is provided with an inner annular recess 22 between bearings 23 which support the eccentric carrying member 17A on the shaft 16, the recess 22 locating the gear teeth 21 to allow the eccentric carrying member 17A and the eccentric 17 to rotate. An outer annular recess 24 is open to the outer surface of the eccentric 17 and merges with the inner recess 22 at the inner dead center position of the eccentric 17. The outer recess 24 encloses an annular set of gear teeth 25 formed on or attached to the inner surface of the rotary piston 18. A pair of bearings 26, one on each side of the annular gear teeth 25, support the rotary piston 18 on the eccentric 17.

Annular spaces 27 and 28 between outer end walls 11 and 15 and inner end walls 12 and 14 respectively, permit free rotation therein of flywheels 29 secured to the eccentric carrying member 17A and incorporating balancing mass for compensating for the off-center mass of the eccentric 17 and rotary piston 18. The bottom flywheel 29 has a bevel gear 30 secured to it and this forms the power output of the engine.

Below the engine and integral with the bottom outer end wall 11, there is secured a shaft casing 31 which carries a shaft 32 extending therethrough. A bevel gear 33 is secured to the shaft 32 and meshes with the gear 30 through an aperture 34 in the bottom outer end wall 11. Two hanger bearings 35 support the shaft 32, these hearings being in close proximity to bevel gear 33. Bearings 36 and 37 and seals 38 and 39, provided in the shaft casing 31, encircle shaft 32. Engine accessories may be driven from end 40 of shaft 32 and the vehicle or other load from the flange 41.

Other features, also common to the known rotary piston engines, are the inlet and exhaust ports 42 and 43 respectively (FIG. 2), the coolant passages 44 and 45 in the side walls and piston respectively, the apex seals 46 urged against the peripheral wall 13, and the flank seals 47 urged against the chamber side walls 12 and 14. In the engine shown in FIGS. 1 and 2, a sump 48 is provided to act as a reservoir for lubricating oil. A fuel injector or spark plug is provided opposite the inlet and exhaust ports and is represented by a box 49 in FIG. 2. Thrust 3 bearings 50 are provided between the eccentric member 17 andrthe end walls lland of the housing.

The operation of the engine is similar to that of n and n+1 rotary piston machines in that the working chambers move with the piston 18 around the cavity 19, successively repeating in each chamber the phases of induction of a charge of air or an air/ fuel mixture through the inlet port 42, compression of the induced charge, burning of the fuel and air together to cause a power delivery phase and exhaust of the products of combustion through the exhaust port 43.

FIG. 3 shows a twin piston rotary piston engine 51 in which parts similar to those already described with reference to FIGS. 1 and 2 are identified with the same reference numerals with the addition of suflices a and b.

It will be seen that the two eccentrics 17a and 17b are phased 180 degrees apart and that an additional wall 12b is incorporated to separate the two working chambers 20a and 20b. It should be noted that there is no center support for the shaft 16a.

FIG. 4 shows a twin piston rotary piston engine 52 in which parts similar to those already described with reference to FIGS. 1 and 2 are identified with the same reference numerals with the addition of suflices c and d.

The two eccentrics 17c and 17d are in phase with each other and in fact form one continuous eccentric 17e. In this case, the pistons are both carried by a tube 53 which projects over the top end of the eccentric 17d and has the piston gear 54 cut in a projection 55. The gear 54 meshes with a small gear 55 cut in the outer surface of the shaft 16c. Part of the flywheel 56 is located at the bottom of the engine between the outer end wall 110 and the inner end wall 12c and incorporates the part of the off-set mass required to balance the eccentrics 17c and 17d, the other part of the flywheel 56 being located between the end walls 140 and 150.

Clearly, combinations of engine and pump units are possible utilizing the present invention; for instance, the invention can be easily employed to provide a unit in which an air compressor of the n and n+1 lobe type is sandwiched between two like engines, the air from the compressor being delivered to the two engines to supercharge them.

A major structural advantage conferred by the foregoing structural aspects of the invention is that the teeth of the gears can be of a width which will reduce the loading on them to enable them to withstand the loads met in practice. The gear teeth can be up to half the width of the piston or more if necessary.

A second major structural advantage is that the smaller gear wheel can be machined directly on the surface of the stationary shaft whereas in prior engines the output shaft had to pass through the smaller gear wheel. The hole available for it to pass through was considerably less than the pitch circle of the smaller gear due to the fact that some metal had to be provided to support the gear teeth.

Yet another major advantage of the invention is that it enables the gears to be placed in the median plane thus preventing incipient toppling of the piston under gear loadings, such as would occur if the engine was provided with gears at the side of the piston as normal hitherto.

The above major advantages all combine to enable a very strong engine to be designed. Thus, a naturally aspirated engine of this kind working on a Diesel cycle, in which high gas pressure gives rise to high torque, becomes a structural possibility. Furthermore, because of the shaft strength it is possible to construct a twin piston Diesel engine without a center support bearing.

Other advantages having a beneficial effect in the production of the engine are as follows. In the twin piston versions, it is possible to employ a sandwich construction of parts, that is: bottom outer end wall, bottom inner end wall, bottom peripheral wall, center wall, top peripheral wall, top inner end wall and top outer end wall without any problem of alignment of the bearings simply because there is no center bearing. A second advantage is that the sump is a natural extension of the bottom outer end wall and does not have to bridge two or more assembled parts. Such an assembly is a source of oil leaks due to inaccurate alignment of the assembled parts for one reason or another.

The provision of a through output shaft can be beneficial in that engine accessories such as water pump and fan etc., can be conveniently grouped in oneaccessible location and driven from one end of the shaft and. th y main power outlet can be from the other. Furthermore, the angle of the drive shaft can be chosen to drive in a wide range of directions by suitable choice of bevel angle.

The power output member need not be a bevel, but can be a V-belt pulley, chain sprocket, spur gear, or any suitable transmission mechanism. It would also be possible to close-couple a hydrostatic pump with the eccentric to provide a hydraulic drive where this is desired.

The engines described can be adapted for use as pumps.

In addition to the structural features, FIGS. 1, 2 and 3 also disclose an improved lubrication system which makes use of the stationary shaft.

Hitherto, in, for example, it and n+1 lobe engines of the epitrochoidal cavity type, lubrication has been difficult due to the fact that high pressure oil has sometimes to be introduced into the engines through a rotating shaft and sometimes from one side of the engine. With the rotating shaft the difliculties are to feed high pressure oil into it and in the case of feeding oil from one side of the engine it has proved ditficult to ensure that the bearings remote from the feed are sufliciently lubricated. One further drawback of engines in which the phasing gears are in close proximity to the flank seals high pressure lubricant supplied to the gears reaches the flank seals. The flank seals are not, in many cases, able to keep the combustion products in the working chambers and keep the high pressure oil out, consequently the oil consumption tends to be unduly high.

The lubrication system of FIG. 1 shows a pump 60 for raising oil from the sump 48 and delivering it under pressure successively through an oil cooler 61 and a filter 62. These are shown in FIGS. 1, 3, 4 and 5 in diagrammatic form for the sake of clarity. The oil pump is driven from the engine shaft 32 and the oil cooler is either sited in an air stream or supplied with cooling fluid. A conduit shown diagrammatically at 63 feeds the oil to a central oilway 64 which branches at two levels into radial passages 65 and 66. These terminate at the surfaces of bearings 23 and some oil from them lubricates these bearings and some passes on through passages 67 in the eccentric carrying member and the eccentric, to the surfaces of bearings 26. Some of the oil delivered by passages 66 seeps along the bearings 22 to the thrust bearings 50 and some travels in the opposite direction to the groove 22 in the eccentric carrying member 17A there to lubricate the gear teeth 21- Seepage from thrust bearings 50 is collected in gullies 68 and passes through passages 69 to groove 24 in the eccentric 17. Flow of oil from passages 67 passes in one direction along the bearings 26 to the vicinity of gears 25, and in the other towards an annular deflector plate 70 which is placed to prevent an excess of oil from reaching the flank seals 47.

Passages 71 and 72 are drilled in the inner surface of the piston and connect the interior 45 of the piston with the groove 24 and with the ends of bearings 26 in the vicinity of the deflector plates 70 to convey oil at low pres sure under the action of acceleration forces tending to move the oil into the piston at the outer dead center position of the eccentric 17, that is the station thereon farthest from the axis of the shaft 16.

In the engine shown in FIG. 3, a twin piston version, the oil supply system is virtually the same as that shown in FIG. 1 and parts already described with reference to FIG. 1 are marked with reference numerals having suffices a and b as before. One small difference is that the oil seepage from the axially outer ends of bearings 26a and b is collected and is ducted back to the passages 71:: and b respectively through passages 73in a cylindrical portion 74 of thetwo part piston 18a and b.

The oil return system now described with reference to FIGS. 1 and'2 is used on the engine of FIG. 3 and reference numerals used in FIGS. 1 and 2 will begiven suffices a and b where used in FIG. 3.

The kinematics of the rotary piston engine now de scribed is such that in the position of the rotary piston shown in FIG. 1 (and FIG. 3) acceleration forces acting on the rotary piston and coolant within it are momentarily all in the direction of arrow X. These forces tend to move the coolant to the left hand end of any pockets there may be within the coolant cavity 45. By placing an exhaust port 75 at each of three symmetrical points on the rotary piston, these points being equi-spaced from adjacent apices 46 on the same side of the rotary piston, it is possible for oil to pass out of the port 75 because the gears are lightly loaded at this point. The acceleration forces urge hot oil through the ports 75 which extend through the radial gear in a radially inward direction. It is also convenient to put a suitable wall in the coolant cavity 45 of the rotary piston at this position to' act as a barrier for oil being swirled circumferentially.

In order to receive the hot oil exhausted from port 75 and convey it to sump 48, two diametrically opposed transverse passages 76 are formed in the shaft 16 and gear wheel 21 and each of these passages 76 intersect a longitudinal drain passage 77 leading through end wall 11 to sump 48.

Referring to FIG. 2, it is known that in the two lobed epitrochoidal engine here described, the pitch circle diameter of the spur gear 21 is 4 times e, the eccentricity, and the annular gear 25 has a pitch circle diameter of 6e. It is also a known fact that the eccentric rotates three times as fast as the piston and that the three points corresponding to the position of the ports 75 approach nearest to the eccentric at two positions which lie on the major axis of the two-lobed epitrochoidal cavity 19. Accordingly, if the transverse passages 76 are aligned with the major axis of the epitrochoidal cavity, the exhaust ports will in turn register with each of them and a transfer of hot oil will take place every time. If the ports 75 are not equidistant from the apices on the same side of the piston, the transverse passage will not be aligned with the major axis of the epitrochoidal cavity.

The relative dimensions of the engine shown in FIG. 5 permit the use of a simplified oil return system. When the ratio R/ e of an engine is large, a certain portion of the piston flank 80 always overhangs the side wall He to a sufiicient extent to allow an axially extending exhaust port 81 to extend through the flank wall to the coolant cavity 452. The dimension R is the distance from the center of the piston to the top of an apex and the dimension 2 is the eccentricity of the eccentric. In FIG. 5, the exhaust port 81 extends to a point close to the lower flywheel 292 and below the upper edge of a conical shield 82 attached to the flywheel.

The port 81 is located equidistant from the apices in a similar manner to exhaust port 75 in FIG. 1, and at the radially innermost zone of the coolant cavity 452 so that oil urged to this zone by acceleration forces will flow out.

Oil trapped by the shield 82 flows away to sump 48e through drillings 83 in the flywheel and an aperture 84 in the end wall He.

The advantages of simplicity and an absence of seals is conferred by the provision of the oil feed system and oil return system described above due to the provision in the engine of a stationary member which can be used to channel oil to and away from the center of the engine and the points where lubrication is most required.

FIGS. 6a and b to 11a and b show power plants in which the common factor is an end wall common to all the engines. The engines may be of the single or twin rotary piston types and one end of the shaft of each and every engine is located in and supported by a common end wall.

FIGS. 6a and 6b show two engine units 610 (which can be single or twin piston units) mounted back-to-back on common end wall 611. The engine unit output members are spur gears 630 and both drive a single spur gear 632 connected to an output flange 641.

FIGS. 7a and 7b show two engine units 710 moun'ted side-by-side on the common end wall 711. Spur gears 730, 732 and output flange 741 transmit the drive.

FIGS. 8a and 8b show four engine units 810 side-by-side mounted on the common wall end 811. Each unit has a spur gear 830 driving a single gear 832 connected to output flange 841.

FIGS. 9a and 9b show a four unit layout in which the engine units 910 are mounted as side-by-side pairs on the common end wall 911. Spur gears 930 mesh with a single spur gear 932 connected to output flange 941.

FIGS. 10a and 10b show a six unit power plant in which the engine units 1010 are mounted as bac-k-to-back pairs in a three cornered side-by-side layout on a common end wall 1011. The flange 1041 is driven successively by spur gears 1032 and 1030.

FIGS. 11a and 11b show an eight unit power plant in which the engine units 1110 are mounted as back-to-back pairs in a four cornered side-by-side configuration on a common end wall 1111. The spur gears 1132 and 1130 provide a drive to flange 1141.

The manner in which the shaft of each engine is mounted on the end wall as by a press fit in a boss 85 (see FIG. 5), enables a power plant of any reasonable size to be made simply from a standard range of engine units.

Modifications in addition to the above described embodiments may be made within the scope of the appended claims, for example a multi-rotary piston rotary piston machine generally as above described may have a shaft (16) common to the rotary pistons, there being separate eccentric carrying members and eccentrics for each piston, the separate eccentric carrying members being drivingly connected by drive means located without the machine housing.

I claim:

1. A rotary piston machine including a housing having a peripheral wall and spaced end walls which together define a cavity within said housing, the peripheral outline of said cavity being trochoidal, a rotary piston rotatably mounted with said cavity, said rotary piston having a peripheral face with a plurality of apex portions thereon and having spaced side faces, said apex portions and said side faces being cooperable with said peripheral wall and said end walls respectively, to define chambers of variable volume within said housing, constraining means interconnecting said housing and said rotary piston whereby said apex portions are constrained during movement to define a closed trochoidal path relative to said housing during relative rotation between the rotary piston and the housing, said constraining means including a stationary shaft extending between and connected to said end walls, and an eccentric carrying member having an eccentric portion thereon, and being rotatably mounted on said shaft, said rotary piston being rotatably mounted on said eccentric, and said eccentric carrying member being adapted to transmit drive to or from said machine.

2. A rotary piston machine according to claim 1, in which said peripheral outline of said cavity and said path defined by said apex portions is epitrochoidal, and said rotary piston has an internally toothed annular gear attached thereto and coaxial therewith and said shaft has an externally toothed spur gear fixed thereto and coaxial therewith and in meshing engagement with said annular gear.

3. A rotary piston machine according to claim 2, in which journalling surfaces for the rotary piston on said eccentric carrying member are disposed to each side of said annular gear.

4. A rotary piston machine according to claim 3, in which said annular and spur gears are arranged in the median plane of the rotary piston.

5. A rotary piston machine according to claim 2, including balance Weights on said eccentric carrying member carried within a hollow portion of one of said end walls.

6. A rotary piston machine according to claim 1, including a flywheel on said eccentric carrying member and carried Within a hollow portion of one of said end Walls.

7. A rotary piston machine according to claim 2, in which said shaft carries a main lubricating oil flow to those machine parts which require lubricating.

8. A rotary piston machine according to claim 7, in which an axially extending oilway is provided through said shaft together with at least one radial passage intersecting said oilway and terminating at its radially outer end at the surface of the shaft in position to deliver oil to a bearing encircling the shaft and supporting said eccentric carrying member thereon.

9. A rotary piston machine according to claim 8, in which passages are provided through the eccentric carrying member and the eccentric portion, said passages leading to a bearing encircling the eccentric portion and supporting said piston thereon, said passages extending from a station on the inner surface of the eccentric carrying member, the path swept by the station being in close proximity to the said radially outer end of said radial passage.

10. A rotary piston machine according to claim 9, in which drain passages are provided leading from the bearings encircling the shaft and the eccentric portion to the meshing annular and spur gears.

11. A rotary piston machine according to claim 9, in which ducts in the rotary piston lead from the vicinity of the bearings encircling the eccentric portion to a coolant cavity in the rotary piston to enable the oil escaping from the bearings encircling the eccentric portion to act as a coolant for the piston.

12. A rotary piston machine according to claim 11, in

which a coolant exhaustport is provided in a flank of the rotary piston at or near the radially innermost point of said coolant cavity and equidistant from the apices on the same side of the rotary piston.

13. A rotary piston machine according to claim 12, in which a shield fixed to a flywheel carried-by said eccentric carrying member acts to channel coolant exhausted from said coolant exhaust port away from the adjacent rotary piston flank.

14. A rotary piston machine according to claim 13, in which said flywheel is carried within a hollow portion of one of said end walls and'there are provided spillways through said flywheel and apertures in the said one wall so that oil collected by said shield may pass through said spillways and apertures to an oil reservoir.

15. A'rotary piston machine according to claim 9, in which said passages through the eccentric carrying member and the eccentric portion extend substantially to that station on the surface of the eccentric portion farthest from the axis of said shaft 16. A rotary piston machine according to claim 7, in which said shaft is provided with a discharge passage for conveying rotary piston coolant away from said rotary piston.

17. A rotary piston machine according to claim 16, in which each of n equiangularly spaced shaft discharge passages for rotary piston coolant are presented radially out wardly through said spur gear and are arranged to be succesively in alignment with one of n+1 inwardly presented coolant dicharge passages extending through said annular gear where n is the number of lobes on said epitrochoidal peripheral outline.

18. A rotary piston machine according to claim 17, in which n equals 2.

References Cited UNITED STATES PATENTS RALPH D. BLAKESLEE, Primary Examiner. 

